Ultrasonic detection system

Abstract

An ultrasonic detection system having a flat faced radiator for providing a narrow beam of ultrasonic energy with minimal dispersion. The system includes an ultrasonic transmitter and receiver unit coupled to an ultrasonic transducer for producing ultrasonic energy. The system also includes a planar radiator and a coupling device between the ultrasonic transducer and the planar radiator. An encapsulating member surrounds the ultrasonic transducer for damping ultrasonic energy transmitted by the transducer in all but one direction. The encapsulating member is also coupled to the planar radiator in areas of the planar radiator that are not coupled to the coupling means. The encapsulating member has an area of increased density immediately adjacent to the planar radiator for damping the ultrasonic energy in areas of the planar radiator that are not directly coupled to the coupling means. This results in a ultrasonic detection system that radiates a relatively narrow beam of ultrasonic energy and in which the encapsulating member is relatively decoupled from the ultrasonic energy. The flat radiating face makes the ultrasonic detection system ideally suited for applications such as level detection and particularly where the radiator must be exposed to sterilizing procedures.

We claim: 
     
       1. An ultrasonic detection system comprising: an ultrasonic transmitter and receiver unit;   an ultrasonic transducer coupled to said ultrasonic transmitter and receiver, for producing ultrasonic energy, said ultrasonic transducer having at least one substantially planar face at its bottom surface;   a substantially flat planar radiator member composed of a rigid material and having top and bottom planar surfaces, said radiator surfaces having a surface area larger than that of said ultrasonic transducer planar face, said planar radiator disposed below said transducer planar face and having portions extending beyond the edges of said transducer planar face;   substantially flat planar coupling means disposed between said ultrasonic transducer planar face and said planar radiator top surface, for transferring said ultrasonic energy from said ultrasonic transducer to said planar radiator;   an encapsulating member substantially surrounding said ultrasonic transducer for damping said ultrasonic energy transmitted by said ultrasonic transducer in all but a downward direction, said encapsulating member also being coupled to the top surface of said planar radiator in said portions of the planar radiator extending beyond the edges of said transducer planar face; and   said encapsulating member having an area of increased density immediately adjacent to the top surface of said planar radiator extending portions for damping the ultrasonic energy in areas of said planar radiator not directly coupled to said coupling means, wherein said planar radiator substantially radiates ultrasonic energy downward from a radiating area directly coupled to said coupling means, said radiating area having a surface area approximately equal to the surface area of said transducer planar face.   
     
     
       2. The ultrasonic detection system of claim 1 wherein said ultrasonic transducer is a piezoelectric transducer. 
     
     
       3. The ultrasonic detection system of claim 1 wherein said coupling means is coupled to both said transducer and said radiator member by means of an adhesive. 
     
     
       4. The ultrasonic detection system of claim 1 wherein said radiator is composed of a metallic material. 
     
     
       5. The ultrasonic detection system of claim 1 wherein said ultrasonic transducer, said coupling means, and said radiator are generally circular in cross-section and the diameter of said ultrasonic transducer and said coupling means are smaller than the diameter of said radiator. 
     
     
       6. The ultrasonic detection system of claim 1 wherein said area of increased density in said encapsulating member is separated from said ultrasonic transducer. 
     
     
       7. The ultrasonic detection system of claim 1 wherein said radiator produces an ultrasonic sound pressure pattern characteristic of a piston radiator. 
     
     
       8. The ultrasonic detection system of claim 1 further comprising means for mounting said ultrasonic transducer, encapsulating member and radiator to a liquid storage tank such that said radiator transmits ultrasonic energy vertically downward into said liquid storage tank. 
     
     
       9. An ultrasonic liquid level detector comprising: an ultrasonic transmitter and receiver unit;   an ultrasonic transducer coupled to said ultrasonic transmitter and receiver, for producing ultrasonic energy, said ultrasonic transducer having at least one substantially planar face at its bottom surface;   a substantially flat planar radiator member composed of a rigid material and having top and bottom planar surfaces, said radiator surfaces having a surface area larger than that of said ultrasonic transducer planar face, said planar radiator disposed below said transducer planar face and having portions extending beyond the edges of said transducer planar face;   substantially flat planar coupling means disposed between said ultrasonic transducer planar face and said planar radiator top surface, for transferring said ultrasonic energy from said ultrasonic transducer to said planar radiator;   an encapsulating member substantially surrounding said ultrasonic transducer for damping said ultrasonic energy transmitted by said ultrasonic transducer in all but a downward direction, said encapsulating member also being coupled to the top surface of said planar radiator in said portions of the planar radiator extending beyond the edges of said transducer planar face;   said encapsulating member having an area of increased density immediately adjacent to the top surface of said planar radiator extending portions for damping the ultrasonic energy in areas of said planar radiator not directly coupled to said coupling means, wherein said planar radiator substantially radiates ultrasonic energy downward from a radiating area directly coupled to said coupling means, said radiating area having a surface area approximately equal to the surface area of said transducer planar face; and   means for mounting said ultrasonic transducer, encapsulating member and planar radiator to a liquid storage tank so that said planar radiator transmits ultrasonic energy downward into said liquid storage tank.   
     
     
       10. The ultrasonic detection system of claim 9 wherein said ultrasonic transducer is a piezoelectric transducer. 
     
     
       11. The ultrasonic detection system of claim 9 wherein said coupling means is coupled to both said transducer and said planar radiator member by means of an adhesive. 
     
     
       12. The ultrasonic detection system of claim 9 wherein said planar radiator is composed of a metallic material. 
     
     
       13. The ultrasonic detection system of claim 9 wherein said ultrasonic transducer, said coupling means, and said planar radiator are generally circular in cross-section and the diameter of said ultrasonic transducer and said coupling means are smaller that the diameter of said planar radiator. 
     
     
       14. The ultrasonic detection system of claim wherein said area of increased density in said encapsulating member is separated from said ultrasonic transducer. 
     
     
       15. The ultrasonic detection system of claim 9 wherein said planar radiator produces an ultrasonic sound pressure pattern characteristic of a piston radiator. 
     
     
       16. Apparatus for housing a flat-faced ultrasonic transducer having a radiator member with top and bottom planar surfaces, said radiator top surface having portions extending beyond the edge of said transducer face the apparatus comprising: substantially flat planar coupling means disposed between a flat face of the transducer and the top surface of the radiator for transferring ultrasonic energy from the transducer to the radiator;   an encapsulating member substantially surrounding the transducer for damping the ultrasonic energy in all but a downward direction, the encapsulating member coupled to the top surface of the radiator in said portion of the radiator extending beyond the edges of said transducer planar face;   said radiator being composed of a rigid material; and   the encapsulating member having an area of increased density immediately adjacent to the top surface of the radiator extending portions for damping ultrasonic energy in areas of the radiator not directly coupled to the coupling means.